Question

Which property allows you to write?

$4 + (3 +9 ) = (4 +3)+9$

Short answer

The property is Associative Property of Addition.

Step-by-step solution

Step-1 – What are real numbers? 

Real numbers are simply the combination of Whole numbers, Integers, Rational and Irrational numbers in the number system.

Step-2 – Associative Property of Addition of Real Numbers: 

Suppose a, b, and c is three real numbers.

Associative property of Addition: (a + b) + c = a + (b + c)

If you are adding three real numbers, the sum is always the same regardless of their grouping.

Example: (11+12) + 13 = 11 + (12+13) = 36

Step-3 – Write the name of the property: 4 + (3 + 9) = (4 + 3) + 9 

Associative property of Addition states, if you are adding three real numbers, the sum is always the same regardless of their grouping.

Associative property of Addition: (a + b) + c = a + (b + c)

Name of the property for this equation 4 + (3 + 9) = (4 + 3) + 9 is Associative property of Addition.